Charged particle beam apparatuses have many functions, in a plurality of industrial fields, including, but not limited to, inspection of semiconductor devices during manufacturing, exposure systems for lithography, detecting devices and testing systems. Thus, there is a high demand for structuring and inspecting specimens within the micrometer and nanometer scale.
Micrometer and nanometer scale process control, inspection or structuring is often done with charged particle beams, e.g. electron beams, which are generated and focused in charged particle beam devices, such as electron microscopes or electron beam pattern generators. Charged particle beams offer superior spatial resolution compared to, e.g. photon beams due to their short wavelengths.
Typically, a charged particle beam device includes several chambers, such as a gun chamber, a specimen chamber or further intermediate chambers. These chambers are separated from each other and can typically be provided to individual levels of vacuum. Typically, the pressure in the gun chamber is lower as compared to the pressure in a specimen chamber. Thereby, vacuum valves are used to isolate vacuum recipients from air and from adjacent vacuum recipients or chambers. It is one desire to improve the vacuum conditions within the charged particle columns of the state of the art devices.
Further, particle generation within a charged particle beam column needs to be considered. If undesired particles are generated in a charged particle beam column or a vacuum recipient thereof, the particles can be detrimental to the vacuum conditions or can, particularly if released over a specimen to be inspected, deteriorate the measurement application by providing undesired particles on the specimen. Thereby, it has to be considered that valves for particle beam systems can have a plurality of tasks and/or requirement. Typically, the valve usually blocks a beam line and separates two vacuum recipients from each other. Further, space requirements have to be considered in light of the fact that the length of the beam path influences the optical properties of the charged particle beam column.
Yet, particle generation in vacuum chambers is also to be considered for other applications, for example processing of substrates in vacuum chambers. Thereby, typically, substrates are provided in a vacuum processing chamber for layer deposition, etching, layer structuring, masking or the like. For these applications, particles on a substrate can also deteriorate the processing process. Accordingly, it is desired for such applications to provide a valve unit with reduced particle generation.
In view of the above, it is an object of the present invention to provide an improved vacuum valve and an improved charged particle beam device that would overcome at least some of the above problems.